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Re: Bitten Ornithopod on This Side Of Hell?




From: Dann Pigdon


> Tim D. wrote-
> >Even that may be dubious if P.Currie is right. He attributed the great
> >variety of LK small theropods to gregarious behavior and pack hunting among
> >tyrannosaurs. In his view, young tyrannosaurs did not hunt small prey such
> >as thescelosaurs but feasted on carcasses of large dinos killed by adults,
> >leaving small predator niches open for other theropods.
> >
>
> But there is still no reason why a young tyrannosaur might not occasionally
> go after smaller prey. Modern day predators do this too, even in species
> where the parents bring them food.


Tyrannosaurs may also have brought smaller, albeit crippled, prey back
for the youngsters to hone their deadly skills on.

As far as Currie's idea is concerned; it may well have been true of
SMALL tyrannosaurs (that is, up to about 3 metres long), but how many
other LK North American theropods ranging between 6-9 metres are known?
There seem to be a lot of predatory theropods up to 3 metres in length,
and a few up to 6 metres, but adult forms between 6 and about 9 metres
seem to be rare. Perhaps very young tyrants were fed until they lost
their 'cuteness factor', so that adolescents of the larger 9-12 metre
species were filling the 6-9 metre predator niche.


I don't know if there was such a niche, since there was also a size gap between the large and small herbivores. Not much was intermediate between the large hadrosaurs and ceratopsids and the small thescelosaurs and leptoceratopsids. Pachycephalosaurs could have been an exception, but not until they became larger in the Lancian.(They may also have been rare or excluded from most lowland environments.) I (and also P. Currie) suggest tyrannosaurs of all ages stayed with the pack and 6-9m tyrannosaurs began to participate in pack hunting, perhaps by leading in pursuit of fleeing prey, if they were exceptionally gracile and fast, and drawing the attention of tougher ceratopsid etc prey from larger tyrannosaurs approaching from a different direction.



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Dann Pigdon Australian Dinosaurs: GIS / Archaeologist http://www.geocities.com/dannsdinosaurs Melbourne, Australia http://www.alphalink.com.au/~dannj/ ________________________________________________________________


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